Many Egyptian customs described by Herodotus are the reversal of a custom that existed in Greece. The explanation is that the ancient Greeks believed that the barbarians on the edges of the earth were the opposite of the civilized people in the middle of the terrestrial disk. Herodotus' description tells a lot more about ancient Greece than about the Egyptians.Herodotus knows more about the Egyptian religion than he finds proper to write down. E.g., he mentions nearly all elements of the legend of Isis and Osiris in passing, but never tells the complete story. (It is known to us from a treatise by the Greek author Plutarch of Chaeronea, who lived c.100 CE.) When Herodotus describes the festivals, sacrifices and rituals of famous Egyptian temples like Memphis, Sais and Heliopolis, he can seldom been shown to err.Although egyptologists regard this logos as a valuable source of information, the accuracy of it has been challenged. His eyewitness accounts seem accurate, but the stories told to him are questioned. Some researchers think that the people who told Herodotus information could have forgotten parts, or just entertained him with an interesting answer that had nothing to do with the truth.His way of describing the holy animals is pretty accurate, but one cannot help but wonder if he ever saw a hippopotamus. His description is closer to a horse with tusks than to the hippo. Now it turns out that at this point, Herodotus is guilty of plagiarism (Eusebius, Preparation to the Gospel 10.3). Perhaps the Halicarnassian researcher has seen the hippo only from a distance and has decided not to trust his defective observation and to rely on another source, Hecataeus of Miletus